FR2995932A1 - METHOD AND APPARATUS FOR COLLECTING A LIGHT SUBMARINE FLUID SUCH AS FRESHWATER OR HYDROCARBONS - Google Patents

Abstract

The invention particularly relates to a device (10, 101, 102) for underwater collection of a light fluid (200) comprising: a first reservoir (11) provided with a first opening (16) and a second opening (233); - a second reservoir (12) covering the first opening (16), surrounding a portion of the first reservoir, and provided with a third opening (19) putting the second reservoir in communication with the medium surrounding the device; connecting means (58) connecting the first and second reservoirs - a first conduit (21) opening into the first reservoir (11), for the densitary transport (57) of a phase of the fluid towards the surface; a structure (234) for guiding and introducing (53) the fluid into the first reservoir (11), which extends into the first reservoir (11) and separates a first portion from the first reservoir in which the second reservoir is provided. opening (233), a second portion of the first reservoir in which extends the end (210) opening of the first conduit (21); and - a fluid collecting structure (92, 235), which extends outside the first reservoir (11), is secured to the first reservoir, and surrounds the second opening (233).

Description

The present invention relates to a method for collecting one or more underwater fluid (s) light (s), in particular a submarine jet containing several phases whose density is lower than that of seawater, and a collection device for the implementation of such a method. The invention applies in particular to the collection of hydrocarbons 10 escaping from a well or conduit in damaged morning and located at great depth, and to the collection of a freshwater underwater source having - or mixed with - a gaseous phase. Unless otherwise expressly or implicitly stated, in the present application, the terms "light" and "heavy" are used with reference to the properties of seawater; thus, the term "light fluid" refers to a fluid whose density is lower than that of seawater. STATE OF THE ART EP1644589 discloses a method and a device for the capture of fresh water from a source under -Marine. The device comprises a first duct whose lower end surrounds the source in a sealed manner, a second duct of smaller diameter than the upper portion of the first duct, and an open base tank covering the upper end of the first duct and trapping air. The lower end of the second conduit is immersed within the upper portion of the first conduit, and the upper end of the second conduit is located above the water-air interface within the reservoir, so that to avoid the pollution of fresh water by sea water, and to limit the hydraulic overload of the source. When the fresh water produced by the source contains a gaseous phase, which can be dissolved in a liquid phase, such a device does not make it possible to separate the gaseous phase from the liquid phase, the two phases being collected and indistinctly driven into the liquid phase. second conduit. Numerous devices have also been proposed for collecting hydrocarbons escaping from a well or a damaged marine conduit. The patent application US2012 / 0155965A1 describes a hydrocarbon collector intended to be connected to a blowout preventer ("BOP") block. As described in particular in the document "A model for simulating deepwater or gas blowouts - Part I: Theory and model formulation", Li Zheng et al, Journal of Hydraulic Research, Vol. 41, No. 4, 2002, pages 339-351, a subsea jet of hydrocarbons forms a plume by rising and mixing with seawater, then forming a "cloud" of droplets. When a hydrocarbon jet escapes into seawater at great depth, the low temperature and high pressure of the seawater promote the formation of "hydrates" which make it difficult to collect the jet. Patent Application US2012 / 0155965A1 discloses a deep hydrocarbon plume collection device which includes a collector cap overlying the plume, a separator tank disposed near the surface, and a riser connecting the plume. bell to the tank. A conduit connecting the reservoir to the atmosphere allows the gases contained in the reservoir to escape, while the liquid phase is pumped and discharged from the reservoir by another conduit in order to keep the reservoir and the riser in a vacuum, to provoke ascent of the hydrocarbon plume mixed with seawater in the riser. In order to limit the formation of hydrates, the bell and the riser are thermally insulated and initially filled with nitrogen and / or helium.

A disadvantage of such a collection system is that it collects a significant amount of seawater mixed with the hydrocarbons and causing the formation of hydrates. Another disadvantage of this system is that it requires a riser of large diameter and great length, resistant to depression and possibly to pressure. Another disadvantage of this system is that it requires a large capacity pump. US4318442 and WO8101310 disclose devices which are deposited on the sea floor to cap a damaged wellhead. US4318442 discloses an apparatus comprising a weighted container having an upper opening, a closure valve of this opening, a gas transport conduit for maintaining a gaseous atmosphere in the container, a liquid conveying conduit opening under the gas head, and vents located below the liquid outlet to compensate for variations in the well leakage rate and output rates of the liquid and gaseous fluids. The container thus delimits a cavity maintained in equilibrium with the seawater surrounding the apparatus, and the liquid hydrocarbons rise in the liquid transport conduit by gravitational (or "densitary") effect, that is to say ie because of the lower density of liquid hydrocarbons, compared to the density of the surrounding seawater. In order to avoid the escape of hydrocarbons by the vents, a pump assists the transport of the liquid hydrocarbons in the liquid transport conduit, so as to entrain seawater. W08101310 discloses an apparatus for collecting liquids. hydrocarbons comprising a liquid and gaseous hydrocarbon phase separation column, and a pump for discharging the liquid phase. Such systems are not suitable for the collection of hydrocarbons at a depth greater than a few hundred meters where the coldness of the seawater mixed with the hydrocarbons causes the formation of hydrates likely to clog the liquid transport pipe and / or the collection device. SUMMARY OF THE INVENTION An object of the invention is to propose a device for collecting an underwater fluid or a mixture of underwater fluids, in particular a submarine source containing one or more phase (s) fluid (s), which is simple to implement. An object of the invention is to propose a device for collecting an underwater fluid or a mixture of underwater fluids, in particular a submarine source (e) containing one or more fluid phase (s). (s), which is adapted to great depths, in particular at depths of at least 500 or 1000 meters, for example at depths ranging from about 1000 meters to about 2000 or 3000 meters. An object of the invention is to propose a method for collecting a light underwater fluid or a mixture of light underwater fluids, and a collection device for carrying out such a method, which are improved and / or at least partially remedying the deficiencies or disadvantages of known underwater fluid collection methods and devices. Unless otherwise expressly or implicitly stated, the terms "enclosure (s)", "receptacle (s)", and "reservoir (s)" are considered synonymous in this application, and are therefore used interchangeably. Unless otherwise explicitly or implicitly indicated, in the present application, the substantive "fluid" designates either a fluid in the liquid and / or gaseous phase, or a slurry comprising a liquid phase and a solid phase, or a mixture of fluids or gaseous phases. (s), liquid (s), and / or solid (s).

According to one aspect of the invention, there is provided an underwater collection device for a fluid whose density is lower than that of seawater, which comprises: a first reservoir for receiving the fluid, which is provided with a first opening and a second opening; a second tank covering the first opening, surrounding a portion of the first tank, and provided with a third opening putting the second tank in communication with the medium surrounding the device; connecting means connecting the first and second tanks; a first duct opening into the first reservoir, for the density transport of at least a first phase of the fluid towards the surface; a structure for guiding and introducing the fluid into the first reservoir, which extends into the first reservoir and separates a first portion of the first reservoir in which the second opening is provided, of a second portion of the first reservoir in the first reservoir; which extends the open end of the first conduit; and a fluid collection structure, which extends outside the first reservoir, is secured to the first reservoir, and surrounds the second opening. The device may comprise a second conduit opening into the second reservoir, for the density transport of at least a second phase of the fluid to the surface. The fluid collection structure, which may be at least partly made of plastics material or elastomer, is preferably flexible or deployable, so as to pass from a picked configuration adapted to the displacement and placement of the device. underwater, to an expanded configuration adapted to the collection of the fluid. The fluid collection structure may consist essentially of a tubular or frustoconical envelope (skirt-shaped); the surface of this structure can be corrugated / wrinkled.

Preferably, the volume of the space delimited by the collection structure when it is deployed is at least equal to the volume of the first tank and / or the volume of the cavity delimited by the first and second tanks.

The device may comprise a third conduit comprising (or forming) said fluid guide and introduction structure as well as said fluid collection structure; in this case in particular, a free end of the third conduit for introducing the fluid into the collection and separation device, can be equipped with a connecting device adapted to the structure (conduit or "BOP" in particular) of which s' escapes the fluid to be collected, for example a device as described in the aforementioned US2012 / 0155965A1 patent application. The invention is particularly applicable to the collection of a liquid hydrocarbon, a mixture of hydrocarbon liquid (s) and gaseous, a mixture of hydrocarbon (s) gas and a sludge comprising a ) liquid hydrocarbon (s) mixed with hydrates, and the collection of fresh water mixed with gas (s) that can be dissolved in fresh water. The invention makes it possible to separate the phases of the collected fluid - or the mixture of fluids - in the containers. The invention makes it possible to absorb variations in the flow rate, the pressure, and / or the composition of the fluid / mixture admitted at the inlet of the device, and / or variations in the exhaust flow rate of the extracted phase (s). (s) fluid / mixture, these variations being able to result in variations in the levels of the respective interfaces between the first and second phases - ie in the first container - and between the second phase and the seawater - ie in the space extending between the first and second containers and communicating with the underwater environment surrounding the device -. The invention makes it possible to transport the phases separated by the device in ducts that are substantially maintained in equilibrium with the surrounding marine environment, which makes it possible to use ducts with low mechanical strength and / or flexible ducts. The enclosures / containers of the device are also substantially maintained in equilibrium with the marine environment, may also have a low mechanical strength and / or a flexible structure. The conduits and / or the containers may in particular comprise a deployable structure, which may be made of plastic or elastomer, in particular an "inflatable" structure comprising a double wall capable of containing seawater. Such structures hoses can contribute to limiting hydrate adhesion to their respective surfaces, and therefore limit the risk of clogging of the device. The invention makes it possible to limit the formation of hydrates by avoiding or limiting contact between liquid hydrocarbons and seawater, and by limiting the contact surface between the gaseous hydrocarbons and the seawater. In another aspect of the invention, there is provided a method of underwater collection of a fluid having at least a first phase whose density is lower than that of seawater, and where appropriate at least one second phase whose density is lower than that of the seawater and that of the first phase, in which: the fluid is introduced into a cavity communicating with the underwater environment so that the cavity is maintained in equipression with this medium, this cavity being delimited by two reservoirs: i) a first reservoir provided with a first opening and a second opening; and ii) a second tank covering the first opening, surrounding at least a portion of the first tank, connected to and communicating with the first tank, and provided with a third opening communicating with the underwater environment; by transporting the fluid in a collection structure which extends outside the first reservoir, which is secured to the first reservoir and surrounds the second opening, and by guiding the fluid by a guide structure which extends into the first reservoir and separates a first portion of the first reservoir in which is provided the second opening, a second portion of the first reservoir in which extends the open end of a first conduit (21) opening into the first reservoir, by promoting the flow of the first phase in the first reservoir, where appropriate the separation of the phases in the cavity and the flow of the second phase in the second reservoir; the first flowing phase (rising) is recovered by difference in density in the first duct; and, where appropriate, recovering the second flowing phase (rising) by difference in density in a second duct opening into the second reservoir. According to embodiments of the invention: the device may comprise a fourth conduit opening into the second reservoir and equipped with a disconnecting (or shut off) member such as a valve, this conduit allowing the introduction of a "flushing" fluid - or "flushing" fluid - used to evacuate (expel) at least part of the seawater contained in the device, before the introduction into the tanks of the fluid to be collected; in this case, it is possible to use a rinsing fluid in liquid or gaseous form whose density (i.e. the density) can be lower than that of the lower density phase of the fluid to be collected; for example, nitrogen can be used; this rinsing fluid can be stored in a - and come from a - third pressure tank connected to the second tank by the fourth conduit; at least part of the wall of the second tank, in particular the part of this wall extending around the first tank, may comprise thermal insulation so as to limit the cooling of the phases of the fluid to be collected by the water; sea surrounding the collection device; for the same purpose, the first and / or second conduit may also include thermal insulation; the first duct may for example be arranged (in particular sized) to facilitate a flow of the first phase in this duct with an average speed ranging from about 0.001 (10-3) meters per second (m / s) to about approximately ten (10) m / s; the second duct may for example be arranged (especially dimensioned) to facilitate a flow of the second phase in this duct with an average speed in a range of about 0.001 10 (10-3) meters per second (m / s) at about ten (10) m / s; the first container may be arranged (especially dimensioned) to allow temporary storage of the first phase in this container; for this purpose, the capacity of this first reservoir may for example be at least equal to the amount of the first phase of the mixture which is collected for a period of time in a range of 0.1 (10-1) second (s). ) approximately one hundred (102) seconds or so; the second container may be arranged (especially dimensioned) to allow temporary storage of the second phase in this container; for this purpose, the capacity of this second reservoir may for example be at least equal to the amount of the second phase of the mixture which is collected for a period of time in a range of 0.1 (10-1) second (s). ) approximately one hundred (102) seconds or so; at least one of the first and second reservoirs, which are at least partially interlocked with one another, may have a general shape of revolution, in particular a substantially cylindrical shape or a spherical cap shape; in the case where these two tanks have an envelope of revolution, the respective axes of revolution of these envelopes may be substantially merged; at least one of said first, second and third ducts may be equipped with at least one disconnecting (or shut-off) device such as a valve or a shutter; - In particular, the device may comprise a shutter disposed at the inlet - or in the vicinity of the inlet - of the second duct, this shutter comprising a movable member - such as a ball or ball - whose density has an intermediate value. between that of the first phase of mixing and that of the second phase of the mixture, so that this movable member can float on the first phase and prohibit the introduction of this first phase in the second conduit; - The collection device may comprise connecting members providing a rigid connection - or weakly deformable - between the first and second containers / tanks; - The collection device may comprise means for positioning reservoirs ensuring the maintenance of the first and second containers / tanks near the place or the structure from which escapes the mixture to be collected; these positioning means may for example comprise cables fixed to the seabed by anchors or by masses resting on the bottom; the collection device may comprise phase separation means, in particular deflecting or separating walls, which are arranged in the first container / reservoir in particular, to promote the mutual separation of the first and second phases at the same time; interior of the first and second containers, to avoid or limit the passage of the second phase in the first conduit, and to avoid or limit the passage of the first phase in the second conduit; the collection device may comprise (at least) two separator modules providing phase separation in equipression with the surrounding submarine environment, which are connected by (at least) a riser; the collection process may comprise the following operations: immersing a collection device to the vicinity of a jet or source of fluid to be collected; stable positioning of the collection device with respect to the structure from which the fluid to be collected escapes, by anchoring to the bottom of the sea and / or by establishing mechanical connections between the collection device and this structure introduction of a fluid rinsing in the first and second tanks to evacuate the sea water; deploying the collection structure around the structure from which the fluid to be collected escapes. Other aspects, features, and advantages of the invention appear in the following description which refers to the appended figures and illustrates, without any limiting character, preferred embodiments of the invention. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic longitudinal sectional view of a device for collecting a light underwater fluid according to one embodiment of the invention. FIGS. 2 to 4 illustrate, in diagrammatic longitudinal sectional view, the steps of a method of collecting a multiphase fluid using the device illustrated in FIG. 1: FIG. 2 corresponds to a step of immersion and positioning the collection device close to the structure from which the fluid to be collected escapes; Figure 3 corresponds to a step of rinsing the collection device with a fluid introduced into the upper part of the second container; FIG. 4 corresponds to a phase separation stage of the fluid collected by the collection device connected to the structure from which the fluid escapes. Figure 5 is a schematic longitudinal sectional view of a device for collecting an underwater fluid according to another embodiment of the invention. Fig. 6 is a schematic cross-sectional view of the collection device illustrated in Fig. 5, and is a view according to VI-VI of Fig. 5.

FIG. 7 schematically illustrates a collection device according to another embodiment, which comprises two separator modules such as those illustrated in FIGS. 1 and 5. FIG. 8 is a schematic longitudinal sectional view of a collection device of a underwater fluid according to another embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION Unless otherwise explicitly or implicitly stated, elements or members - structurally or functionally - identical or similar are designated by identical reference numerals in the various figures. With reference to FIGS. 1 and 5 in particular, the collection device 10 consists essentially of two open containers or reservoirs 11, 12, of two or three ducts 21 to 23 opening into these reservoirs, as well as a collection structure. extending in the first reservoir 11. In the embodiment corresponding to FIGS. 1 to 4 and 7, the first reservoir 11 comprises a cylindrical lateral wall 14 extending along an axis of revolution, and a wall 15 of 20 bottom closing a first longitudinal end of the wall 14, and pierced with a hole 233 passage of the collected fluid. The second longitudinal end 16 of the wall 14, which is not closed, forms an upper opening for the tank 11. In this embodiment, the second tank 12 has a cylindrical side wall 17 extending in the same axis 30 of revolution, and a bottom wall 18 closing a first longitudinal end of the wall 17. The second longitudinal end 19 of the wall 17, which is not closed, forms a lower opening for the tank 12. It can be seen in FIGS. 1 and 8 in particular that the bottom 15 of the first reservoir 11 extends substantially in the same plane as the opening 19 of the second reservoir, so that the first reservoir 11 extends substantially entirely inside the reservoir. the cylindrical cavity delimited by the second reservoir 12. In contrast, in the embodiment corresponding to FIGS. 5 and 6, the first reservoir 11 extends in part only inside the cavity In this embodiment, the first and second reservoirs 11, 12 each comprise a double wall in the form of a portion of a sphere extending along the same axis of revolution and in the form of a portion of a sphere delimited by the second reservoir. the same center 40. In the embodiments shown, the tanks 11, 12 extend along a common axis. In the embodiments shown, the upper opening 16 of the first reservoir 11 extends facing the bottom 18 of the second reservoir 12, while the side wall 17 and the opening 19 of the second reservoir 12 extend around the first reservoir, at a distance from the latter, delimiting with the side wall 14 of the first reservoir 11, a peripheral space 50. This peripheral space 50, which is annular in the embodiment of Figures 1 to 4 and 8, and of toroidal shape in the embodiment of FIGS. 5 and 6, opens (communicates) with the medium in which the device 10 is placed, through the lower opening 19 of the reservoir 12, and opens (communicates) with the cavity delimited by the tank 11, at its upper end surrounding the upper opening 16 of the tank 11. 25 The peripheral space 50 allows the circulation 51 of the seawater entering - or leaving - this space by the or 19. As illustrated in FIGS. 1 and 5 in particular, the containers 11 and 12 are rigidly interconnected by means of bars 58 connecting the respective lateral walls 14, 17 of the containers 11 and 12, and extending without in the peripheral space 50. In the embodiment illustrated in FIGS. 1 to 4, the collection device 10 comprises a third duct 23, which extends through the opening 233 of the bottom 15 of the tank 11, is open at its lower end 230 extending outside the tank 11, to allow the introduction 52, in the device 10, the mixture to be collected. The third conduit 23 is also open at its upper (internal) end 232 extending inside the tank 11, to allow the introduction 53, in the device 10, of the mixture that it carries. It can be seen in FIGS. 1 to 4 that the lower (outer) end 230 of the duct 23 is equipped with a connecting member 231 adapted to the structure 20 from which escapes (see the arrows 200 FIGS. ) the fluid / mixture to be collected. This connecting member 231 is schematically shown in the form of a flange adapted to a complementary flange 201 fitted to the conduit 20, but may take various other forms. In the embodiment illustrated in FIGS. 1 to 4, the upper part 234 of the third duct 23, which extends inside the tank 11, forms a structure for guiding and introducing the fluid into this reservoir, while the lower portion 235 of the third conduit 23, which extends outside the reservoir 11, forms a structure 20 for collecting the fluid. In the embodiment illustrated in FIG. 8, the third duct 23, which extends completely inside the tank 11, forms the structure for guiding and introducing the fluid into this reservoir, while the collection structure fluid comprises an envelope 92 which extends beneath the first reservoir 11 to which it is secured, and which surrounds the second opening 233 provided in the bottom of the reservoir 11. The fluid collection envelope 92 may comprise a layer of plastics material or elastomer, and a reinforcing structure such as a filamentary metal structure shaped helically extending along the axis 30 of general symmetry of the device. Such a collection structure can thus pass from a picked configuration adapted to the displacement and the installation of the device under water, which is illustrated in FIG. 5, to an expanded configuration adapted to the collection of the fluid, which is illustrated in FIG. 8. In the embodiment illustrated in FIG. 5, the structure for guiding and introducing the fluid into the reservoir 11 essentially consists of the wall 64. In the embodiments shown, the device 10 comprises a first conduit 21, which extends through the bottom 18 of the reservoir 12, is open at its lower (internal) end 210 extending inside the reservoir 11, to allow the introduction 54, 10 in the conduit 21, of the phase the densest of the collected mixture - ie of the first phase - that has elapsed and if necessary accumulated in the reservoir 11. The conduit 21 forms - or is extended by - a riser that can extend on the surface of the sea and allowing gravity transport of the first phase from the first reservoir. In the embodiments shown in FIGS. 1 to 7, the device 10 comprises a second conduit 22, which also extends through the bottom 18 of the reservoir 12, is open at its lower end 220 through which it opens into the interior of the container. reservoir 12, above the reservoir 11, to allow the introduction 55, in the conduit 22, of the lightest phase of the collected mixture which separated from the mixture by gravity and if necessary accumulated in the The duct 22 forms - or is extended by - a riser which can extend to the surface 94 of the sea and permit the gravitational transport of the second phase from the second tank. In contrast, in the embodiment illustrated in FIG. 8, the collection device 10 comprises only an "embryo" of conduit 22 which is equipped with a valve and which opens into the underwater environment to serve as a vent, in order to evacuate any excess of the phase 30 accumulated in the sky of the bell-shaped tank 12. It can be seen in FIG. 1 that the first reservoir comprises a wall 60 extending above the outlet orifice 232 of the conduit 23, and in the extension of this conduit, so that the wall 60 can deflect a jet 53 of the collected mixture leaving the conduit 23, which causes or facilitates the separation of the phases of the mixture; the same applies to the stream 53 of collected fluid leaving the peripheral duct 65, FIG. 5. In the embodiment of FIGS. 5 and 6, the first tank comprises a deflector wall 64 in the form of a portion of a spherical cap whose center 40 is substantially coincident with that of the walls 14, 15, 17, 18 of the tanks 11 and 12.

The walls 14, 15 and 64 thus delimit, inside the reservoir 11, a space or duct 65 in the form of a thick spherical blade and / or corolla, at the lower end of which opens the conduit 23 carrying the collected mixture, and which opens into the tank 11, under the opening 16 of the latter.

The mixture leaving the duct 23 then circulates in this duct 65 where its speed and its pressure can decrease, and where the phases can separate, to the upper outlet of this duct 65 where the phases of the mixture flow into the cavities 70, 71 respectively delimited by the tanks 11, 12.

In the embodiment of FIGS. 5 and 6, the tanks 11, 12 and the ducts 21 to 23 have a symmetry of revolution along the axis 30, the ducts 21 to 23 extending along this common axis, the duct 21 extending into the duct 22. In all the embodiments, the phase separation of the fluid / mixture leaving the duct 23, 65, 234 is effected in particular by gravity in the cavity 70 delimited by the tank 11 and in the portion 71 of the cavity delimited by the reservoir 12 which extends above the cavity 70. The interface 72 between these two phases, which is substantially horizontal, normally extends into the cavity 70 of the reservoir 11, while that the interface 73 between the lightest phase present in the sky of the tank 12, and the seawater surrounding the device, normally extends into the peripheral cavity 50 separating the respective walls of the tanks 11, 12. The separation phases of mixing is notably favored by the fact that the lower end 210 of the duct 21, through which the "heavy" phase collected in the tank 11 "escapes" is located under the upper end 230 of the duct 23, 65, 234 through which the fluid is introduced into the cavities 70, 71, and at a significant distance from this end 230. With reference to FIGS. 1 to 4 in particular, the device 10 comprises a fourth conduit 24 opening into the second reservoir 12 and equipped with a valve 80 isolation, and a third tank 13 connected to the reservoir 12 through the conduit 24 and containing a pressurized flushing fluid for discharging seawater contained in the device after immersion.

With reference to FIG. 8, the device 10 comprises a fifth conduit 25 opening into the second reservoir 12 and equipped with an isolation valve 800, and a fourth reservoir 130 connected to the reservoir 12 via the conduit 25 and containing an inhibiting fluid , for example methanol, serving to limit or avoid the formation of hydrates in the peripheral space 50. The ducts 21 to 23 and the walls 14, 15, 17, 18 of the first and second reservoirs may be made of a resistant material to marine corrosion, in particular of metal or a plastic material or an elastomer, and may comprise a double wall capable of being filled with seawater. At least part of the peripheral wall 17 of the second reservoir may thus be or otherwise, provided with a thermal "barrier" limiting the cooling of the fluids present in the cavity 50 by the seawater surrounding the second reservoir.

On the other hand, at least a portion of the peripheral wall 14 of the first reservoir, in particular the portion of this wall extending opposite the interface 73, may be made of metal, for example, in order to form a "bridge" thermal promoting the heating of the fluids present in the cavity 50 by the fluid contained in the first reservoir. With reference to FIGS. 1 to 4 in particular, the device 10 5 comprises a shutter disposed in the vicinity of the inlet 220 of the second conduit 22. This shutter comprises a movable member 81 in the form of a ball whose density has an intermediate value between that the first phase of mixing and that of the second phase of mixing.

The shutter further comprises a guide 82 for the member 81, in particular a cage extending into the reservoir 12, in the extension of the conduit 22, and in which the ball 81 can move. Thus, the ball is held by gravity in the lower part of the guide 82, as long as it is not surrounded by a fluid of higher density than its own, and can then leave the first phase contained in the sky and the cavity 71 of the reservoir 12, escape (see the arrows 55) from the reservoir 12 via the conduit 22, to the sea surface. On the other hand, if the level of the first phase in the reservoir 12 reaches or exceeds the the lower end of the guide 82 supporting the ball 81, the ball 81 then floats on the first phase, and can rise in the cage 82 until contact with the end 220 of the conduit 22, closing the conduit 22 and then prohibiting the introduction of the first phase - as well as the second phase - into this path.

According to other embodiments, an isolation valve, a shutter, and / or a device for regulating the flow rate of material transported may also equip the ducts 21 to 23, as represented in FIG. 22. With reference to FIGS. 2 to 4 in particular, for the collection of a mixture 200 of two phases of distinct and lower densities than that of seawater, which escapes from a structure 20 underwater, in the vicinity of the submarine bottom 90, it is possible to successively carry out the following operations: - the device 10 is immersed near the bottom 90 and the structure 20 and the position of the collection device is stabilized by its anchoring at bottom 90 with the aid of cables 91, and / or by establishing a mechanical connection between the device 10 and the structure 20, as illustrated in FIG. 2, so that the axis 30 is substantially vertical, whereas the opening 16 extends in a substantially horizontal plane in upper part of the tank 11, and the opening 19 extends in a substantially horizontal plane 10 in the lower part of the tank 12; the valve 80 is then opened to introduce into the tanks 11, 12 the rinsing fluid contained in the tank 13, to evacuate at least the majority of the sea water "trapped" in the tanks 11, 12 during the immersion of the device, as illustrated in FIG. 3; the lower end 230 of the duct 23 is connected to the structure 20 as tightly as possible. The same procedure is used when a collection device is used, such as those illustrated in FIGS. 5 and 8, whose structure The collection structure 92 is firstly positioned above the point of emergence of the fluid to be collected, then is deployed downwardly surrounding the zone or structure from which the fluid escapes. fluid to collect, substantially to the bottom 90 submarine, on which the base of this structure can rest by means of flanges 93 filled with a composition denser than seawater, for example filled with sand. This results in the introduction of the mixture jet 200 into the cavities 70, 71, 50 of the device which communicate with the underwater environment so that these cavities are maintained in equipression with this medium.

The configuration described above of the tanks 11, 12 and ducts 21 to 23 in particular then favors the separation of the phases contained in the mixture, the flow of the "heaviest" phase in the first reservoir, and the flow the lightest phase in the second tank. It is thus possible to recover the heavy phase flowing by difference in density in the first duct 21, as well as the light phase 5 flowing also by difference in density in a second duct 22, as illustrated in FIG. operation of the collection device, the interface 72 is established between the dimension - measured along the axis 30 - of the opening 16 and that of the end 210 of the conduit 21, while the interface 73 is established at an intermediate dimension between that of the opening 16 and that of the opening 19. The height - ie the length measured along the axis 30 - separating the opening 16 from the container 11 and the lower opening 210 of the duct 21, determines the maximum variation of the level of the interface 72 separating the two separate phases: if this interface rises above the opening 16, the heavy phase can then flow to the outside of the tank 11, in the space 50 delimited by the walls of the tanks see 11, 12, and where appropriate to the outside of the tank 12 and the device 10.

This height determines, with the diameter - or equivalent diameter - of the wall 14 of the tank 11, the useful capacity of this tank. Furthermore, if this interface 72 is lowered below the opening 210 of the duct 21, the latter can be defused and the gravitational bearing of the heavy phase in the duct 21 can be interrupted. Similarly, the height measured along the axis 30 and separating the respective openings 16, 19 of the containers 11, 12, determines the maximum variation of the level of the interface 73 separating the light phase and the seawater in the peripheral space 50: if this interface rises above the opening 16, the seawater can then flow inside the tank 11, whereas if this interface 73 is lowered below the 19 opening of the reservoir 12, the (or) phase (s) of the mixture contained in the space 50 can escape to the outside of the tank 12 through the opening 19. Referring to Figure 7, the device comprises two phase separation modules 101, 102 and a duct 300 connecting these two modules. Each of the modules 101, 102 is identical to the collection and separation device illustrated in FIGS. 1 to 4; in other embodiments not shown, at least one of these modules may be identical or similar to the device illustrated in Figures 5 and 6, or may have other shapes and configurations. FIG. 7 shows that the duct 300 connects the outlet of the duct 21 of the lower module 101, which serves to transport the heavy phase delivered by this module, to the inlet duct 23 of the upper module 102. This modular device thus makes it possible to provoke successively Two phase separations: a first separation of the collected mixture, in the first module 101, and a second separation of several phases transported by the conduit 21 of the module 101, in the second module 102.

Claims (4)

CLAIMS1 - Device (10, 101, 102) for underwater collection of a fluid (200) whose density is lower than that of seawater, characterized in that it comprises: a first reservoir ( 11) for receiving the fluid, which is provided with a first opening (16) and a second opening (233); a second reservoir (12) covering the first opening (16), surrounding a portion of the first reservoir, and provided with a third opening (19) putting the second reservoir in communication with the medium surrounding the device; connecting means (58) for connecting the first and second reservoirs; - a first conduit (21) opening into the first reservoir (11), for the densit transport (57) of at least a first phase of the fluid to the surface (94); a structure (64, 234) for guiding the fluid and for introducing (53) the fluid into the first reservoir (11), which extends into the first reservoir (11) and separates a first portion of the first reservoir in 20 which is provided the second opening (233), a second portion of the first reservoir in which extends the end (210) opening of the first conduit (21); and a fluid collecting structure (92, 235), which extends outside the first reservoir (11), is secured to the first reservoir, and surrounds the second opening (233). 2 - Device according to claim 1 which comprises a second conduit (22) opening into the second reservoir (12) for the density transport (56) of at least a second phase of the fluid to the surface. 3 - Device according to any one of claims 1 or 2 30 wherein the structure (92, 235) for collecting the fluid, which is preferably at least partly made of plastic or elastomer, is flexible or deployable, in order to pass from a configured configuration adapted to the displacement and the installation of the device under water, to an expanded configuration adapted to the collection of the fluid. 4 - Device according to any one of claims 1 to 3 which comprises a third conduit (23) comprising said structure (234) for guiding and introducing the fluid and said structure (92, 235) for collecting the fluid, and wherein a free end (230) of the third conduit (23) is provided with a connecting device (231) adapted to the structure (20) from which the fluid (200) to be collected escapes. - Device according to any one of claims 1 to 4 which comprises a fourth conduit (24) opening into the second reservoir (12) and equipped with a member (80) sectioning or shutter, for the introduction of a flushing fluid for discharging seawater contained in the device. 6 - Device according to claim 5 which comprises a third reservoir (13) for the pressurized storage of the rinsing fluid, which is connected to the second reservoir (12) by the fourth conduit (24). 7 - Device according to any one of claims 1 to 6 wherein at least a portion of the wall of the second reservoir (12), in particular the portion of this wall extending around the first reservoir (11), comprises a thermal insulation so as to limit the cooling of the phases of the fluid to be collected by the seawater surrounding the device (10). 8 - Device according to any one of claims 1 to 7 wherein the first and optionally the second conduit (s) (21, 22) comprises (s) a thermal insulation. 9 - Device according to any one of claims 1 to 8 wherein at least one of the first and second tanks (11, 12) 30 comprises a structure (14, 15, 17, 18) flexible or deployable, which can be made of plastics material or elastomer, in particular an inflatable structure having a double wall.A device according to any one of claims 1 to 9 wherein the first and second reservoirs (11, 12), which are at least partially - Nested one inside the other, extend along a common axis (30), and in particular have substantially revolution forms whose respective axes (30) of revolution are substantially merged. 11 - Device according to any one of claims 1 to 10 wherein at least one of said first, and optionally second, and third conduit (s) (21, 22, 23) is equipped with at least one cutter or shutter member (81, 82) such as a ball valve or shutter (81), and / or a flow control member. 12 - Device according to claim 2 and optionally any one of claims 3 to 11, which comprises a shutter disposed in the vicinity of the inlet (220) of the second conduit (22), said shutter comprising a member (81) mobile whose density has an intermediate value between that of the first phase of the fluid and that of the second phase of the fluid, so that this member (81) can float mobile on the first phase and prohibit the introduction of this first phase in the second leads. 13 - Device according to any one of claims 1 to 12 which comprises means (91) for positioning the tanks (11, 12) for maintaining the first and second tanks / tanks near the place or structure (20) from which the fluid to be collected escapes, such as cables fixed to the seabed by anchors or by masses resting on the bottom. 14 - Device according to any one of claims 1 to 13 which comprises phase separation means, in particular walls (60, 64) deflectrices or separatrices, which are arranged in the first tank / reservoir, for to promote the mutual separation of first and second phases of the fluid inside the first and second tanks, to avoid or limit the passage of the second phase in the first conduit, and if necessary to avoid or limit the passage of the. first phase in the second conduit. 15 - Device for sub-marine collection of a fluid (200) light which comprises at least two modules or devices (10, 101, 102) according to any one of claims 1 to. 14, each module providing phase separation of the fluid in equipression with the surrounding submarine environment, the modules being connected by at least one riser (300). 16 - Method for submarine collection of a fluid (200) comprising at least a first phase whose density is lower than that of seawater, and where appropriate at least one second phase whose density is lower to that of the seawater and that of the first phase, in which: - the introduction (53) of the fluid is introduced into a cavity (50, 70, 71) communicating with the underwater environment so that the cavity is maintained in equipression with this medium, this cavity being delimited by two reservoirs i) a first reservoir (11) provided with a first opening (16) and a second opening (233); and a second reservoir (12) covering the first opening, surrounding at least a portion of the first reservoir, connected to and communicating with the first reservoir, and provided with a third opening (19) communicating with the underwater environment; by transporting the fluid in a collection structure (92, 235) which extends outside the first reservoir (11), which is secured to the first reservoir and surrounds the second opening (233), and by guiding fluid through a guiding structure (234) which extends into the first reservoir (11) and separates a first portion of the first reservoir in which is provided the second opening (233), a second portion of the first reservoir in which extends the end (210) opening of a first conduit (21) opening into the first reservoir (11), promoting the flow of the first phase in the first reservoir, where appropriate the phase separation in the cavity and the flow of the second phase in the second reservoir; the first flowing phase (rising) is recovered by difference of density in the first duct (21); and, where appropriate, recovering the second flowing phase (rising) by density difference in a second duct (22) opening into the second tank (12). 17 - The method of claim 16 which comprises the following operations: immersion of a device (10) for collecting up close to a jet or a source (200) of fluid to be collected; stable positioning of the collection device (10) with respect to the structure (20) from which the fluid to be collected escapes, by anchoring to the bottom (90) and / or by establishing mechanical connections between the collection device and this structure (20); introducing a rinsing fluid into the first and second tanks (11, 12) for discharging seawater therefrom; deploying the collection structure (92, 235) around the structure (20) from which the fluid to be collected escapes. 18 - The method of claim 17 wherein a flushing fluid in liquid or gaseous form and whose density is lower than that of the lower density phase of the fluid to be collected. 19 - Process according to any one of claims 16 to 18 wherein the collected fluid consists essentially of a liquid hydrocarbon, a mixture of liquid and gaseous hydrocarbons, or a mixture of hydrocarbon gas and a sludge comprising a liquid hydrocarbon (s) mixed with hydrates. 20 - Process according to any one of claims 16 to 18 wherein the collected fluid is essentially constituted by fresh water mixed with - or containing - a (or) gas.s 21 - Process according to any one Claims 16 to 20 in which a device (10, 101, 102) according to any one of Claims 1 to 15 is used.